Mobile communication devices have become increasingly common in current society for providing wireless communication services. The prevalence of these mobile communication devices is driven in part by the many functions that are now enabled on such devices. Increased processing capabilities in such devices means that mobile communication devices have evolved from being pure communication tools into sophisticated mobile multimedia centers that enable enhanced user experiences.
Concurrent to supporting the wide-area wireless communication technologies, such as long-term evolution (LTE) and fifth-generation new radio (5G-NR), the mobile communication devices may form an Internet-of-Things (IoT) network with a number of non-conventional communication devices (e.g., vehicle, home appliances, sensors, etc.) to enable a variety of human-machine interactive applications. In contrast to the RF signals communicated in a wide-area wireless network, RF signals communicated in the IoT network are often modulated at a lower modulation bandwidth (e.g., less than 180 KHz) and communicated sporadically as opposed to being communicated periodically or continuously.
Envelope tracking (ET) is a technique whereby an ET modulated voltage is provided to an amplifier circuit for amplifying the RF signal. The ET modulated voltage is associated with a time-variant voltage envelope that tracks closely a time-variant amplitude envelope of the RF signal being amplified. In this regard, the peaks and lows of the ET modulated voltage can be generated in accordance to the peaks and lows of the RF signal to help improve linearity and efficiency of the amplifier circuit. However, it may be challenging to maintain the ET modulated voltage at a peak level for a sufficient duration (e.g., 2 micro seconds) for amplifying a lower modulation bandwidth (e.g., <180 KHz) RF signal to a defined power level (e.g., +26 dBm), particularly when the ET modulated voltage is generated based on a lower battery voltage (e.g., <3.2 V). As such, it may be desirable to maintain the ET modulated voltage at the peak level for the desired duration without compromising error vector magnitude (EVM) of the amplifier circuit.